Determination of ELF-wave characteristics most strongly reacting to minor changes of ionospheric electron density in a high-latitude region

In this paper, we use numerical experiment methods to address the problem of determining characteristics of ULF (0.3-3 kHz) electromagnetic waves recorded in the surface layer and providing the maximum amount of information about the Earth-ionosphere waveguide. We have analyzed the effect of the horizontal spatial structure of electron density of the Earth-ionosphere waveguide on propagation of electromagnetic waves. We have identified characteristics that allow us to record them by instrumental methods in conditions of weakly disturbed ionosphere. The density profiles used in numerical experiments have been obtained from data acquired by the Partial Reflection Radar at the Polar Geophysical Institute, located at the radiophysical observatory Tumanny in the Murmansk Region (69.0° N, 35.7° E), and by the IRI2016 model during the March 15, 2013 solar flare and the subsequent magnetic storm on March 17, 2013. The electromagnetic signal propagation model used in this work is the adaptation of gas-hydrodynamic methods to electrodynamic applications. The model is based on the scheme of upwind approximation of spatial derivatives (Godunov’s method with correction of streams). We also use splitting by spatial directions and physical processes. Signal field attenuation due to conductivity and its rotation due to Hall conductivity of the medium are considered in separate splitting steps by analytical formulas.